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Cast iron is just that-cast. It is expensive to make sheet stock because it must be sawn from a large cast boule. You can buy sawn bar stock, but it is rough and expensive. There is a product called Dura-bar. I don't recall the sizes, but you might check into that.

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WOW,I also needed 3/16 CI Sheet 3 years ago for a project. Needed 3 sq feet and never found it.
The thinnest I found was 1/2 inch.
As I recall, Mc Master Carr has some (1/4?)
Anyway, figure on 50 bucks a sq ft and then the machining time to get it to size..

Green Bay, WI

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Wait a minute !
I just reread your post..
You want round plate..
I found that.. Its used for cams for screw machines..found 3/16 and 1/4 thick 9 inch dia with 1 inch holes as i recall, but that did not cut it for me.. no holes !
Check out some old screw machines shops.
The source I had is now gone..they were closing down when a friend told me..
Good Luck

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The brakes are for a university built Formula SAE car. This is a design event where engineering students design and build open wheel, open cockpit racecars. Here we do 100% of our welding and about 80% of the machining. The only jobs we send out are things we don't have the equipment for...like the splined shafts I've brought up in other posts. Great experience.

As far as the plate goes, I've got requests for quotes in for durabar at a couple of companies. The barbell idea has occured to me, and Paul was not the first person to recomend a skillet. Another painfully obvious idea was to get old car rotors from a junkyard and turn them to size. We'll see how it goes.

Looking forward to anymore ideas!

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JDF...what about some of the new composite rotors that some of the newer cars are using? I'm going to put some on my car soon. They are a lot lighter. You're makin me drool building that car. I spent a whole day climbing under and over David Empringhams Formula car several years ago. Fantastic engineering! Stole lots of ideas for the race stuff I build.
Russ

I have tools I don't even know I own...

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I think using OEM rotors is probably the best and safest way to go about this. If you give us the final dimension and mounting provision you're looking for perhaps one of us has experience with a rotor that is already near net.

If you have a website to validate your FSAE involvment perhaps you could ask someone in the business to help steer you in the right direction. Here's some interesting links.

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My guess is that cast iron is used because it can be cast with ventilation slots, maybe it offers some other benefits like quieter braking (guessing), but I wouldn't be happy with 3/16" cast iron, especially not if made from weights etc!!

You could get them laser cut from steel with all the groovy curved slots, holes etc you need.

This is just an idea, I am no brake expert, but my guess is that motorcycle rotors are steel??

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I'd love to find some production rotors that would fit the application but time is limited (2 weeks) and weight would be a problem. Our car will weigh around 600 pounds with driver, and be braking from speeds typically no greater than 70 MPH. Its a tight course to keep speeds down. 3/16 is a typical thickness for rotors in this competition. Some go even thinner with no problem.

I am not opposed to using steel. We went with stainless the last two years, but weight and machinability were a problem. The real problem is I don't have enough time left to really look into different options. Basically, I've seen 3/16 cast rotors work, so that was what we were going to shoot for...no way to solve an engineering problem, but saves a hell of a lot of time.